Opiates are of course still used as cough suppressants; the most common is
codeine, which is still used for severe coughs (although some research
suggests it is no better than DXM). Other opiates have been used for severe
cough. As an interesting bit of trivia, heroin was first marketed for cough
suppression.

The recreational effects of opiates are fairly well known, and are in any
case beyond the scope of the DXM FAQ.